A1[0]:
 [   0   0   0   0   0]
 [   0  -1  -2  -3  -4]
 [   0  -2  -4  -6  -8]

A1[1]:
 [   0   1   2   3   4]
 [   1   1   1   1   1]
 [   2   1   0  -1  -2]

A1[2]:
 [   0   2   4   6   8]
 [   2   3   4   5   6]
 [   4   4   4   4   4]

A1[3]:
 [   0   3   6   9  12]
 [   3   5   7   9  11]
 [   6   7   8   9  10]

